NOT APPLICABLE
NOT APPLICABLE
NOT APPLICABLE
1. Field of the Invention
This invention relates to a disc cartridge holding a disc-shaped recording medium, and particularly to a disc cartridge from which the recording medium can be removed.
2. Description of the Related Art
Examples of disc-shaped recording media include optical discs and the like. Such discs are often housed inside a disc cartridge to prevent grease and dirt on hands from getting onto the recording part of the disc and to make handling of the disc easier.
Disc cartridges in related art generally have had the kind of form shown in Japanese Unexamined Patent Publication No. 161848/1996, in which a disc-shaped medium is rotatably housed inside a case made up of an upper case half and a lower case half, the case having an access opening and a shutter for opening and closing the access opening with a U-shaped cross section.
Thus, in related art disc cartridges, numerous parts in addition to the two shell halves are needed so that the disc is not exposed. Because the front of the disc cartridge case, which is the upper half, and the rear of the disc cartridge case, which is the lower half, are generally asymmetrical, the two case halves have had different shapes and have each had to be molded separately. For these reasons there has been a limit to how far the cost of the disc cartridge can be reduced, and this has been a factor preventing the cost of a disc cartridge containing a recording medium from being reduced.
As a result of reductions in data writing defects due to adaptive recording control responsive to the disc surface, reductions in data misrecognition achieved through repeat playback of the same location, and improved error correction processing, the reliability of recording and playback technologies has been markedly improving. This improvement in recording and playback technologies makes possible improving recording and playback performance if normal storage and usage to prevent the adhesion of dust to the surface of the disc is carried out.
However, even with improved recording and playback technologies, it is still difficult to prevent deterioration of recording and playback performance resulting from grease from hands, etc., getting onto the recorded part of a disc. For a disc which is not used in a disc cartridge, dirt or grease adhering to a disc is mainly caused by user handling who accidentally touch the recording part. On the other hand, when a disc cartridge is used, there is no touching of the disc, and the adhesion of dirt can be largely prevented.
This invention reduces the number of parts in a disc cartridge and thereby reduces its cost while maintaining the required reliability and freedom of use by placing importance only on the prevention of dirtying of the disc by the user. To achieve this and other objects, the invention provides a disc cartridge having a case member with a base surface area larger than that of the disc; an access window provided in the case member for a recording/playback device to access the disc; and a shutter for opening and closing the access window. The disc has a recording portion on only one side thereof, and the disc cartridge has only one case member.
The recording part on the recording side of the disc is substantially shielded from external harm by the case member and the shutter, and the non-recording side of the disc is substantially exteriorly exposed by the disc cartridge. Preferably, the case is an integral unit molded in resin, and the case member and the shutter have flanges to prevent the disc from falling out of the disc cartridge.
The projection of a flange provided on the shutter onto the same plane as the plane of the disc overlaps the disc when the shutter has closed the access window, and does not overlap the disc when the shutter has opened the access window.
This construction enables a lower-cost disc cartridge with fewer parts than prior art disc cartridges, but with comparable or better cleanliness.